U.S.-Denmark Cooperative Research on Damage Evolutions and their Sensitivities during Metal Forming Process

该奖项支持亚利桑那大学的Abhijit Chandra与丹麦技术大学固体力学系的Viggo Tvergaard在材料工程研究方面进行合作。他们对金属的成形和对影响成品性能的工艺有共同的兴趣。特别是，他们的合作研究侧重于了解损伤簇中微缺陷相互作用产生的局部不稳定性现象。特弗加德教授为塑性和蠕变情况下的损伤演化开发了各种模型。钱德拉教授在金属成形工艺和这些工艺的设计敏感性方面做了大量工作。这种互补的专业知识在拟议的合作研究计划中非常有效地结合在一起。在金属成形过程中，工件材料受到强烈的应力场和变形场的影响。结果，材料经历了大的塑性应变和旋转，以产生新的和所需的工件形状。然而，应力场和变形场可能会引起局部不稳定性，从而可能形成微观空洞。这种缺陷的增长会导致成品的机械性能退化，甚至可能导致其失效。所提出的研究结果将非常有助于设计成形工艺，以避免或最大限度地减少这种损伤在工件中的发展。

This award supports Abhijit Chandra of the University of Arizona to collaborate in materials engineering research with Viggo Tvergaard of the Department of Solid Mechanics of the Technical University of Denmark. They share an interest in the forming of metal and in understanding the processes that affect the properties of the finished product. In particular, their collaborative research focuses on understanding the phenomenon of local instabilities generated by interactions of microdefects in a damage cluster. Professor Tvergaard has developed various models for damage evolutions in situations involving plasticity and creep. Professor Chandra has worked extensively on metal forming processes and on design sensitivities of these processes. This complementary expertise is combined very effectively in the proposed collaborative research plan. During a metal forming process, the workpiece material is subjected to intense stress and deformation fields. As a result, the material undergoes large plastic strains and rotations in order to produce new and desirable shapes of the workpiece. However, the stress and deformation fields may cause local instabilities that may nucleate microscopic voids. Growth of such defects results in degradation of the mechanical properties of the finished product, and may even lead to its failure. The results of the proposed research will be very helpful in designing forming processes that avoid or minimize the development of this damage in the workpiece.